Show alert failure for reloading unpacked extensions with bad manifest

chrome/browser/extensions/extension_error_reporter.h

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_EXTENSIONS_EXTENSION_ERROR_REPORTER_H_
 #define CHROME_BROWSER_EXTENSIONS_EXTENSION_ERROR_REPORTER_H_
 
 #include <string>
 #include <vector>
 
+#include "base/observer_list.h"
 #include "base/strings/string16.h"
 
 namespace base {
 class MessageLoop;
 class FilePath;
 }
 
 class Profile;
 
 // Exposes an easy way for the various components of the extension system to
 // report errors. This is a singleton that lives on the UI thread, with the
 // exception of ReportError() which may be called from any thread.
 // TODO(aa): Hook this up to about:extensions, when we have about:extensions.
 // TODO(aa): Consider exposing directly, or via a helper, to the renderer
 // process and plumbing the errors out to the browser.
 // TODO(aa): Add ReportError(extension_id, message, be_noisy), so that we can
 // report errors that are specific to a particular extension.
 class ExtensionErrorReporter {
  public:
+  class Observer {
+   public:
+    virtual ~Observer() {}
+
+    // Called when an unpacked extension fails to load.
+    virtual void OnLoadFailure(const base::FilePath& extension_path,
+                               const std::string& error) = 0;
+  };
+
   // Initializes the error reporter. Must be called before any other methods
   // and on the UI thread.
   static void Init(bool enable_noisy_errors);
 
   // Get the singleton instance.
   static ExtensionErrorReporter* GetInstance();
 
   // Report an extension load error. This forwards to ReportError() after
   // sending an EXTENSION_LOAD_ERROR notification.
   // TODO(rdevlin.cronin): There's a lot wrong with this. But some of our
   // systems rely on the notification. Investigate what it will take to remove
   // the notification and this method.
   void ReportLoadError(const base::FilePath& extension_path,
                        const std::string& error,
                        Profile* profile,
                        bool be_noisy);
 
   // Report an error. Errors always go to VLOG(1). Optionally, they can also
   // cause a noisy alert box.
   void ReportError(const base::string16& message, bool be_noisy);
 
   // Get the errors that have been reported so far.
   const std::vector<base::string16>* GetErrors();
 
   // Clear the list of errors reported so far.
   void ClearErrors();
 
+  void AddObserver(Observer* observer);
+
+  void RemoveObserver(Observer* observer);
+
  private:
   static ExtensionErrorReporter* instance_;
 
   explicit ExtensionErrorReporter(bool enable_noisy_errors);
   ~ExtensionErrorReporter();
 
   base::MessageLoop* ui_loop_;
   std::vector<base::string16> errors_;
   bool enable_noisy_errors_;
+
+  ObserverList<Observer> observers_;
 };
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_ERROR_REPORTER_H_